• Menu
  • Product
  • Email
  • PDF
  • Order now

  • DRV421 Integrated Magnetic Fluxgate Sensor for Closed-Loop Current Sensing

    • SBOS704B May   2015  – March 2016 DRV421

      PRODUCTION DATA.  

  • CONTENTS
  • SEARCH
  • DRV421 Integrated Magnetic Fluxgate Sensor for Closed-Loop Current Sensing
  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Pin Configuration and Functions
  6. 6 Specifications
    1. 6.1 Absolute Maximum Ratings
    2. 6.2 ESD Ratings
    3. 6.3 Recommended Operating Conditions
    4. 6.4 Thermal Information
    5. 6.5 Electrical Characteristics
    6. 6.6 Typical Characteristics
  7. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1  Fluxgate Sensor
      2. 7.3.2  Integrator-Filter Function and Compensation Loop Stability
      3. 7.3.3  H-Bridge Driver for Compensation Coil
      4. 7.3.4  Shunt Sense Amplifier
      5. 7.3.5  Overrange Comparator
      6. 7.3.6  Voltage Reference
      7. 7.3.7  Overload Detection and Control
      8. 7.3.8  Magnetic Core Demagnetization
      9. 7.3.9  Search Function
      10. 7.3.10 Error Flag
    4. 7.4 Device Functional Modes
  8. 8 Application and Implementation
    1. 8.1 Application Information
      1. 8.1.1 Magnetic Core Design
      2. 8.1.2 Protection Recommendations
    2. 8.2 Typical Application
      1. 8.2.1 Closed-Loop Current Sensing Module
        1. 8.2.1.1 Design Requirements
        2. 8.2.1.2 Detailed Design Procedure
        3. 8.2.1.3 Application Curves
      2. 8.2.2 Differential Closed-Loop Current Sensing Module
        1. 8.2.2.1 Design Requirements
        2. 8.2.2.2 Detailed Design Procedure
        3. 8.2.2.3 Application Curve
      3. 8.2.3 Using the DRV421 in ±15-V Sensor Applications
  9. 9 Power-Supply Recommendations
    1. 9.1 Power-Supply Decoupling
    2. 9.2 Power-On Start Up and Brownout
    3. 9.3 Power Dissipation
      1. 9.3.1 Thermal Pad
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
  11. 11Device and Documentation Support
    1. 11.1 Documentation Support
      1. 11.1.1 Related Documentation
    2. 11.2 Community Resources
    3. 11.3 Trademarks
    4. 11.4 Electrostatic Discharge Caution
    5. 11.5 Glossary
  12. 12Mechanical, Packaging, and Orderable Information
  13. IMPORTANT NOTICE

Package Options

Mechanical Data (Package|Pins)
  • RTJ|20
    • MPQF156F
Thermal pad, mechanical data (Package|Pins)
  • RTJ|20
    • QFND504A
Orderable Information
  • sbos704b_oa
  • sbos704b_pm
search No matches found.
  • Full reading width
    • Full reading width
    • Comfortable reading width
    • Expanded reading width
  • Card for each section
  • Card with all content

 

DATA SHEET

DRV421 Integrated Magnetic Fluxgate Sensor for Closed-Loop Current Sensing

1 Features

  • High-Precision Integrated Fluxgate Sensor
    • Offset and Drift: ±8 µT max, ±5 nT/°C typ
  • Extended Current Measurement Range
    • H-Bridge Output Drive: ±250 mA typ at 5 V
  • Precision Shunt Sense Amplifier
    • Offset and Drift (max): ±75 µV, ±2 µV/°C
    • Gain Error and Drift (max): ±0.3%, ±5 ppm/°C
  • Precision Reference
    • Accuracy and Drift (max): ±2%, ±50 ppm/°C
    • Pin-Selectable Voltage: 2.5 V or 1.65 V
    • Selectable Ratiometric Mode: VDD / 2
  • Magnetic Core Degaussing Feature
  • Diagnostic Features: Overrange and Error Flags
  • Supply Voltage Range: 3.0 V to 5.5 V
  • Fully Specified Over the Extended Industrial Temperature Range of –40°C to +125°C

2 Applications

  • Closed-Loop DC- and AC-Current Sensor Modules
  • Leakage Current Sensors
  • Industrial Monitoring and Control Systems
  • Overcurrent Detection
  • Frequency, Voltage, and Solar Inverters

3 Description

The DRV421 is designed for magnetic closed-loop current sensing solutions, enabling isolated, precise dc- and ac-current measurements. This device provides both, a proprietary integrated fluxgate sensor, and the required analog signal conditioning, thus minimizing component count and cost. The low offset and drift of the fluxgate sensor, along with an optimized front-end circuit results in unrivaled measurement precision.

The DRV421 provides all the necessary circuit blocks to drive the current-sensing feedback loop. The sensor front-end circuit is followed by a filter that can be configured to work with a wide range of magnetic cores. The integrated 250-mA H-Bridge drives the compensation coil and doubles the current measurement range, as compared to conventional single-ended drive methods. The device also provides a precision voltage reference and shunt sense amplifier to generate and drive the analog output signal.

Device Information(1)

PART NUMBER PACKAGE BODY SIZE (NOM)
DRV421 WQFN (20) 4.00 mm × 4.00 mm
  1. For all available packages, see the package option addendum at the end of the datasheet.

Typical Application

DRV421 sch_bos704.gif

4 Revision History

Changes from A Revision (July 2015) to B Revision

  • Added TI Design Go
  • Added last two Applications bullets Go
  • Changed QFN to WQFN in pin configuration drawing Go
  • Changed QFN to WQFN in Thermal Information table Go
  • Changed QFN to WQFN in Power Dissipation section Go

Changes from * Revision (May 2015) to A Revision

  • Released to productionGo

5 Pin Configuration and Functions

RTJ Package
20-Pin WQFN
Top View
DRV421 po_bos704.gif

Pin Functions

PIN I/O DESCRIPTION
NAME NO.
AINN 14 I Inverting input of shunt sense amplifier
AINP 13 I Noninverting input of shunt sense amplifier
DEMAG 18 I Degauss control input
ER 19 O Error flag; open-drain, active low output
GND 7, 10, 16, 17 — Ground reference
GSEL0 1 I Gain and bandwidth selection input 0
GSEL1 20 I Gain and bandwidth selection input 1
ICOMP1 12 O Output 1 of compensation coil driver
ICOMP2 11 O Output 2 of compensation coil driver
OR 15 O Shunt sense amplifier overrange indicator; open-drain, active-low output
REFIN 5 I Common-mode reference input for the shunt sense amplifier
REFOUT 4 O Voltage reference output
RSEL0 3 I Voltage reference mode selection input 0
RSEL1 2 I Voltage reference mode selection input 1
VDD 8, 9 — Supply voltage, 3.0 V to 5.5 V. Decouple both pins using 1-µF ceramic capacitors placed as close as possible to the device. See the Power-Supply Decoupling and Layout sections for further details.
VOUT 6 O Shunt sense amplifier output
PowerPAD™ — Connect thermal pad to GND

6 Specifications

6.1 Absolute Maximum Ratings

over operating free-air temperature range (unless otherwise noted) (1)
MIN MAX UNIT
Voltage Supply voltage (VDD to GND) –0.3 7 V
Input voltage, except pins AINP and AINN (2) GND – 0.5 VDD + 0.5
Shunt sense amplifier inputs (pins AINP and AINN) (3) GND – 6.0 VDD + 6.0
Current Pins ICOMP1 and ICOMP2 (short circuit current ISC) (4) –300 300 mA
Shunt sense amplifier inputs pins AINP and AINN –5 5
All remaining pins –25 25
Temperature Junction, TJ max –50 150 °C
Storage, Tstg –65 150
(1) Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings only, which do not imply functional operation of the device at these or any other conditions beyond those indicated under Recommended Operating Conditions. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.
(2) Input terminals are diode-clamped to the power-supply rails. Input signals that can swing more than 0.5 V beyond the supply rails must be current limited, except for the shunt sense amplifier input pins.
(3) These inputs are not diode-clamped to the power supply rails.
(4) Power-limited; observe maximum junction temperature.

6.2 ESD Ratings

VALUE UNIT
V(ESD) Electrostatic discharge Human-body model (HBM), per ANSI/ESDA/JEDEC JS-001(1) ±2000 V
Charged-device model (CDM), per JEDEC specification JESD22-C101(2) ±1000
(1) JEDEC document JEP155 states that 500-V HBM allows safe manufacturing with a standard ESD control process.
(2) JEDEC document JEP157 states that 250-V CDM allows safe manufacturing with a standard ESD control process.

6.3 Recommended Operating Conditions

over operating free-air temperature range (unless otherwise noted)
MIN NOM MAX UNIT
VDD Supply voltage 3.0 5.0 5.5 V
TA Specified ambient temperature range –40 125 °C

6.4 Thermal Information

THERMAL METRIC (1) SBOS704 UNITS
RTJ (WQFN)
20 PINS
RθJA Junction-to-ambient thermal resistance 34.1 °C/W
RθJC(top) Junction-to-case (top) thermal resistance 33.1 °C/W
RθJB Junction-to-board thermal resistance 11.0 °C/W
ψJT Junction-to-top characterization parameter 0.3 °C/W
ψJB Junction-to-board characterization parameter 11.0 °C/W
RθJC(bot) Junction-to-case (bottom) thermal resistance 2.1 °C/W
(1) For more information about traditional and new thermal metrics, see the Semiconductor and IC Package Thermal Metrics application report, SPRA953.

6.5 Electrical Characteristics

All minimum and maximum specifications at TA = +25°C, VDD = 3.0 V to 5.5 V, and ICOMP1 = ICOMP2 = 0 mA (unless otherwise noted). Typical values are at VDD = 5.0 V.
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
FLUXGATE SENSOR FRONT-END
Offset (1) No magnetic field –8 ±2 8 µT
Offset drift No magnetic field ±5 nT/°C
Noise f = 0.1 Hz to 10 Hz 17 nTrms
Noise density f = 1 kHz 1.5 nT/√Hz
Saturation trip level for pin ER 1.7 mT
AOL DC open-loop gain 16 V/µT
AC open-loop gain GSEL[1:0] = 00, at 3.8 kHz,
integration-to-flatband corner frequency		 8.5 V/mT
GSEL[1:0] = 01, at 3.8 kHz,
integration-to-flatband corner frequency		 38
GSEL[1:0] = 10, at 1.9 kHz,
integration-to-flatband corner frequency		 25
GSEL[1:0] = 11, at 1.9 kHz,
integration-to-flatband corner frequency		 70
IICOMP Peak current at pins ICOMP1 and ICOMP2 VICOMP1 – VICOMP2 = 4.2 VPP,VDD = 5 V,
TA = –40°C to +125°C		 210 250 mA
VICOMP1 – VICOMP2 = 2.5 VPP, VDD = 3.3 V,
TA = –40°C to +125°C		 125 150
VICOMP Voltage swing at pins ICOMP1 and ICOMP2 20-Ω load, VDD = 5 V, TA = –40°C to +125°C 4.2 VPP
20-Ω load, VDD = 3.3 V, TA = –40°C to +125°C 2.5
Common-mode output voltage at pins ICOMP1 and ICOMP2 VREFOUT V
SHUNT SENSE AMPLIFIER
VOO Output offset voltage VAINP = VAINN = VREFIN, VDD = 3.0 V –0.075 ±0.01 0.075 mV
Output offset voltage drift –2 ±0.4 2 µV/°C
CMRR Common-mode rejection ratio, RTO (2) VCM = −1 V to VDD + 1 V, VREFIN = VDD / 2 –250 ±50 250 µV/V
PSRRAMP Power-supply rejection ratio, RTO VDD = 3.0 V to 5.5 V, VCM = VREFIN –50 ±4 50 µV/V
VIC Common-mode input voltage range –1 VDD + 1 V
ZIND Differential input impedance 16.5 20 23.5 kΩ
ZIC Common-mode input impedance 40 50 60 kΩ
G Gain, VOUT / (VAINP – VAINN) 4 V/V
EG Gain error –0.3% ±0.02% 0.3%
Gain error drift –5 ±1 5 ppm/°C
Linearity error RL = 1 kΩ 12 ppm
Voltage output swing from negative rail
(OR pin trip level)		 VDD = 5.5 V, IVOUT = 2.5 mA 48 85 mV
VDD = 3.0 V, IVOUT = 2.5 mA 56 100
Voltage output swing from positive rail
(OR pin trip level) 		VDD = 5.5 V, IVOUT = –2.5 mA VDD – 85 VDD – 48 mV
VDD = 3.0 V, IVOUT = –2.5 mA VDD – 100 VDD – 56
ISC Short-circuit current VOUT connected to GND –18 mA
VOUT connected to VDD 20
Signal overrange indication delay (OR pin) VIN = 1-V step 2.5 to 3.5 µs
BW–3dB Bandwidth 2 MHz
SR Slew rate 6.5 V/µs
Settling time, large-signal ΔV = ± 2 V to 1% accuracy, no external filter 0.9 µs
Settling time, small-signal ΔV = ± 0.4 V to 0.01% accuracy 8 µs
en Output voltage noise density, RTO f = 1 kHz, compensation loop disabled 170 nV/√Hz
VREFIN Input voltage range at pin REFIN TA = –40°C to +125°C GND VDD V
VOLTAGE REFERENCE
VREFOUT Reference output voltage at pin REFOUT RSEL[1:0] = 00, no load 2.45 2.5 2.55 V
RSEL[1:0] = 01, no load 1.6 1.65 1.7
RSEL[1:0] = 1x, no load 45 50 55 % of VDD
Reference output voltage drift RSEL[1:0] = 00, 01 –50 ±10 50 ppm/°C
Voltage divider gain error drift RSEL[1:0] = 1x –50 ±10 50 ppm/°C
PSRRREF Power-supply rejection ratio RSEL[1:0] = 00, 01 –300 ±15 300 µV/V
Load regulation RSEL[1:0] = 0x, load to GND or VDD,
ΔILOAD = 0 mA to 5 mA, TA = –40°C to +125°C		 0.15 0.35 mV/mA
RSEL[1:0] = 1x, load to GND or VDD,
ΔILOAD = 0 mA to 5 mA, TA = –40°C to +125°C		 0.3 0.8
ISC Short-circuit current REFOUT connected to VDD 20 mA
REFOUT connected to GND –18
DIGITAL INPUTS/OUTPUTS
Logic Inputs (CMOS)
VIH High-level input voltage TA = –40°C to +125°C 0.7 × VDD VDD + 0.3 V
VIL Low-level input voltage TA = –40°C to +125°C –0.3 0.3 × VDD V
Input leakage current 0.01 µA
Logic Outputs (Open-Drain)
VOH High-level output voltage Set by external pull-up resistor V
VOL Low-level output voltage 4-mA sink 0.3 V
POWER SUPPLY
IQ Quiescent current IICOMP1 = IICOMP2 = 0 mA, 3.0 V ≤ VDD ≤ 3.6 V, TA = –40°C to +125°C 6.5 9 mA
IICOMP1 = IICOMP2 = 0 mA, 4.5 V ≤ VDD ≤ 5.5 V, TA = –40°C to +125°C 8.1 11
VRST Power-on reset threshold 2.4 V
(1) Fluxgate sensor front-end offset can be reduced using the Magnetic Core Demagnetization feature.
(2) Parameter value referred to output (RTO).

6.6 Typical Characteristics

at VDD = 5 V and TA = +25°C (unless otherwise noted)
DRV421 D001_SBOS704.gif
VDD = 5 V
Figure 1. Fluxgate Sensor Front-End Offset Histogram
DRV421 D003_SBOS704.gif
Figure 3. Fluxgate Sensor Front-End Offset vs
Supply Voltage
DRV421 D005_SBOS704.gif
Figure 5. Fluxgate Sensor Front-End Offset Drift
Histogram
DRV421 D007_SBOS704.gif
Figure 7. Fluxgate Sensor Saturation (ER Pin) Trip Level Histogram
DRV421 D009_SBOS704.gif
Figure 9. Fluxgate Sensor Front-End DC Open-Loop Gain vs Temperature
DRV421 D011_SBOS704.gif
Figure 11. Voltage Swing at ICOMPx Pins vs
Negative Peak Current
DRV421 D013_SBOS704.gif
RLOAD = 20 Ω
Figure 13. Negative Voltage Swing at ICOMPx Pins vs Temperature
DRV421 D015_SBOS704.gif
VDD = 5 V
Figure 15. Shunt Sense Amplifier Offset Histogram
DRV421 D017_SBOS704.gif
Figure 17. Shunt Sense Amplifier Offset vs Temperature
DRV421 D019_SBOS704.gif
Figure 19. Shunt Sense Amplifier Common-Mode Rejection Ratio Histogram
DRV421 D021_SBOS704.gif
Figure 21. Shunt Sense Amplifier Power-Supply Rejection Ratio Histogram
DRV421 D023_SBOS704.gif
Figure 23. Shunt Sense Amplifier AINP Input Impedance Histogram
DRV421 D025_SBOS704.gif
Figure 25. Shunt Sense Amplifier AINN Input Impedance Histogram
DRV421 D027_SBOS704.gif
Figure 27. Shunt Sense Amplifier Gain Error Histogram
DRV421 D029_SBOS704.gif
Figure 29. Shunt Sense Amplifier Gain vs
Frequency
DRV421 D031_SBOS704.gif
Figure 31. OR Pin Trip Level vs Output Current
DRV421 D033_SBOS704.gif
Figure 33. OR Pin Trip Delay vs Temperature
DRV421 D035_SBOS704.gif
Figure 35. Shunt Sense Amplifier Output Short-Circuit Current vs Supply Voltage
DRV421 D049_SBOS704.gif
Falling Edge
Figure 37. Shunt Sense Amplifier Small-Signal
Settling Time
DRV421 D051_SBOS704.gif
Falling Edge
Figure 39. Shunt Sense Amplifier Large-Signal
Settling Time
DRV421 D037_SBOS704.gif
VDD = 3.3 V
Figure 41. Shunt Sense Amplifier Overload Recovery Response
DRV421 D039_SBOS704.gif
Figure 43. Reference Voltage Histogram
DRV421 D041_SBOS704.gif
Figure 45. Reference Voltage Drift Histogram
DRV421 D043_SBOS704.gif
Figure 47. Reference Voltage vs Reference Output Current
DRV421 D045_SBOS704.gif
Figure 49. Reference Voltage Load Regulation Histogram
DRV421 D047_SBOS704.gif
Figure 51. Power-On Reset Threshold vs Temperature
DRV421 D002_SBOS704.gif
VDD = 3.3 V
Figure 2. Fluxgate Sensor Front-End Offset Histogram
DRV421 D004_SBOS704.gif
Figure 4. Fluxgate Sensor Front-End Offset vs
Temperature
DRV421 D006_SBOS704.gif
Figure 6. Fluxgate Sensor Front-End Noise Density vs
Noise Frequency
DRV421 D008_SBOS704.gif
Figure 8. Fluxgate Sensor Front-End DC Open-Loop Gain Histogram
DRV421 D010_SBOS704.gif
Figure 10. Fluxgate Sensor Front-End AC Open-Loop Gain vs Frequency
DRV421 D012_SBOS704.gif
Figure 12. Voltage Swing at ICOMPx Pins vs
Positive Peak Current
DRV421 D014_SBOS704.gif
RLOAD = 20 Ω
Figure 14. Positive Voltage Swing at ICOMPx Pins vs Temperature
DRV421 D016_SBOS704.gif
VDD = 3.3 V
Figure 16. Shunt Sense Amplifier Offset Histogram
DRV421 D018_SBOS704.gif
Figure 18. Shunt Sense Amplifier Offset vs Supply Voltage
DRV421 D020_SBOS704.gif
Figure 20. Shunt Sense Amplifier Common-Mode Rejection Ratio vs Input Signal Frequency
DRV421 D022_SBOS704.gif
Figure 22. Shunt Sense Amplifier Power-Supply Rejection Ratio vs Ripple Frequency
DRV421 D024_SBOS704.gif
Figure 24. Shunt Sense Amplifier AINP Input Impedance vs Temperature
DRV421 D026_SBOS704.gif
Figure 26. Shunt Sense Amplifier AINN Input Impedance vs Temperature
DRV421 D028_SBOS704.gif
Figure 28. Shunt Sense Amplifier Gain Error vs Temperature
DRV421 D030_SBOS704.gif
Figure 30. Shunt Sense Amplifier Linearity vs
Supply Voltage
DRV421 D032_SBOS704.gif
Figure 32. OR Pin Trip Level vs Temperature
DRV421 D034_SBOS704.gif
Figure 34. Shunt Sense Amplifier Output Short-Circuit Current vs Temperature
DRV421 D048_SBOS704.gif
Rising Edge
Figure 36. Shunt Sense Amplifier Small-Signal
Settling Time
DRV421 D050_SBOS704.gif
Rising Edge
Figure 38. Shunt Sense Amplifier Large-Signal
Settling Time
DRV421 D036_SBOS704.gif
VDD = 5 V
Figure 40. Shunt Sense Amplifier Overload Recovery Response
DRV421 D038_SBOS704.gif
Figure 42. Shunt Sense Amplifier Output Voltage Noise Density vs Noise Frequency
DRV421 D040_SBOS704.gif
Figure 44. Reference Voltage vs Temperature
DRV421 D042_SBOS704.gif
Figure 46. Reference Voltage vs Supply Voltage
DRV421 D044_SBOS704.gif
Figure 48. Reference Voltage Power-Supply Rejection Ratio Histogram
DRV421 D046_SBOS704.gif
Figure 50. Quiescent Current vs Temperature

 
Texas Instruments

© Copyright 1995-2025 Texas Instruments Incorporated. All rights reserved.
Submit documentation feedback | IMPORTANT NOTICE | Trademarks | Privacy policy | Cookie policy | Terms of use | Terms of sale